Aluminosilicate catalyst, a process for the manufacture thereof and a process for the skeletal isomerization of linear olefins

Abstract

A novel family of substantially amorphous aluminosilicate catalysts and a process for the manufacture thereof are described. In the process, a source of silica, a source of alumina and a source of an alkali metal are mixed in an aqueous medium and then subjected to hydrothermal treatment at a temperature of from 20 DEG C. to 200 DEG C. for a period of from 1 hour to 250 hours, the reaction conditions and duration being selected so as to produce a solid which is substantially amorphous. The invention also extends to the use of the calalyst in acid catalyzed reactions such as the skeletal isomerization of normal olefins, in particular normal butene, and to the use of the catalyst as a support in metal catalyzed reactions.

I claim: 
     
       1. A process for the manufacture of a catalyst suitable for use in acid catalyzed reactions, or as a support in metal catalysed reactions, including the steps of: (a) mixing a source of alumina, a source of silica and a source of an alkali metal in an aqueous medium so as to form a reaction mixture;   (b) subjecting the reaction mixture of step (a) to hydrothermal treatment, at a temperature of from 20° C. to 200° C., for a period of from 1 hour to 250 hours, so as to allow the source of silica to react with the source of alumina to form an aluminosilicate solid and an aqueous solution, the reaction conditions and duration being selected such as to produce a solid which is at least 76% amorphous; and   (c) separating the solid from the aqueous solution.   
     
     
       2. A process as claimed in claim 1, wherein, in step (a), at least one of a source of phosphorus and a source of metal is mixed with the source of alumina, the source of silica and the source of an alkali metal. 
     
     
       3. A process as claimed in claim 1, wherein step (a) is carried out in the presence of a suitable template. 
     
     
       4. A process as claimed in claim 1, wherein step (b) conditions and durations are selected such that the solid obtained is at least 90% amorphous. 
     
     
       5. A process as claimed in claim 1, wherein tile solid obtained from step (c) is washed with water in a washing step (d), until the water is substantially free of excess ions. 
     
     
       6. A process as claimed claim 5, wherein step (d) is followed by a step (e) in which the solid obtained from step (d) is calcined in air at a temperature of from 300° C. to 800° C., for a period of from 0.5 hours to 20 hours. 
     
     
       7. A process as claimed in claim 6, including an additional step (f) in which the calcined product of step (e) is subjected to ion exchange at a temperature of from 10° C. to 100° C., with an aqueous solution of an ammonium salt or of a strong acid. 
     
     
       8. A process as claimed in claim 7, wherein the ammonium form of the catalyst is subjected, in a further step (g), to further washing until it is substantially free of excess ions. 
     
     
       9. A process as claimed in claim 8, wherein, subsequent to step (g), the ammonium form of the catalyst is calcined in air, in a step (h), at a temperature of from 300° C. to 800° C. 
     
     
       10. A process as claimed in claim 1, wherein the source of silica is selected from sodium silicate, colloidal silica, waterglass, fumed silica, silicic acid, silica gel, tetra ethyl orthosilicate, or a combination thereof. 
     
     
       11. A process as claimed in claim 1, wherein the source of alumina is selected from sodium aluminate, a simple aluminium salt, an oxide of aluminium, a hydroxide of aluminium, or a combination thereof. 
     
     
       12. A process as claimed in claim 3, wherein the template is selected from tetra propyl ammonium bromide, pyridine, piperidine, ammonia, or a combination thereof. 
     
     
       13. A process as claimed in claim 12, wherein, in step (a), the molar ratio of the template to the silica is between 1:200 and 1:1. 
     
     
       14. A process as claimed in claim 1, wherein, in step (a), the molar ratio of silica to alumina in the reaction mixture is between 1000:1 and 1:1000. 
     
     
       15. A catalyst suitable for use in acid catalysed reactions or as a support in metal catalysed reactions, comprising a mixed oxide reaction product of a source of silica and a source or alumina, wherein the molar ratio of silica to alumina present in the mixed oxide reaction product is from 1000:1 to 1:1000 and the mixed oxide reaction product is at least 76% amorphous. 
     
     
       16. A catalyst as claimed in claim 15, comprising a mixed oxide reaction product of a source of silica, a source of alumina and a source of phosphorus pentoxide, wherein the molar ratio of silica to alumina present in the reaction product is in the range of 1:1 to 1:10. 
     
     
       17. A catalyst as claimed in claim 16, comprising a metal oxide, the ratio of the metal oxide to alumina being from 1:1 to 1:10. 
     
     
       18. A process for the manufacture of a catalyst suitable for use in acid catalyzed reactions, or as a support in metal catalyzed reactions, comprising the steps of: a) forming an aqueous solution of sodium aluminate, an aqueous solution of a template, and a slurry of silica, the sodium aluminate solution and template solution then being mixed with the silica slurry in such manner as to produce a reaction mixture wherein the molar ratio of silica to alumina varies from about 1000:1 to 1:1000 and the molar ratio of template to silica varies from about 1:200 to 1:1;   b) subjecting the reaction mixture of step (a) to hydrothermal treatment by heating the mixture at a temperature of from about 30° C. to 200° C. for a period of time ranging from about 1 hour to about 96 hours, the reaction conditions and duration of reaction being selected so as to produce a solid which is at least 76% amorphous; and   c) separating the solid from the aqueous solution.   
     
     
       19. A process according to claim 18, wherein the molar ratio of silica to alumina in the reaction mixture varies from about 500:1 to 5:1, and the molar ratio of template to silica varies from about 1:20 to 1:2. 
     
     
       20. A process according to claim 18 wherein the template is tetrapropyl ammonium bromide and the silica is fumed silica. 
     
     
       21. The process according to claim 18 wherein the reaction conditions and duration are selected so as to produce a solid which is at least 90% amorphous. 
     
     
       22. The process according to claim 1 wherein the catalyst or support produced is a zeolite or a molecular sieve. 
     
     
       23. The process according to claim 22, wherein the zeolite or molecular sieve is a ZSM 5 or a ferrierite.